Thermotherapy device

ABSTRACT

This invention relates to the working end of a medical instrument that applies energy to tissue. In one embodiment, the instrument has a microfluidic tissue-engaging surface fabricated by soft lithography means together with optional superlattice cooling means that allows for very precise control of energy application, for example in neurosurgery applications. The tissue-engaging surface can eject a high-heat content vapor into the engaged tissue for treating tissue, while the superlattice cooling structure can prevent collateral thermal damage. Also, the superlattice cooling structure can be used to localize heat at a selected depth in tissue and prevent surface ablation. Also, the superlattice cooling structure can be used to prevent tissue sticking to a thermal energy delivery surface. In another embodiment, the tissue-engaging surface can be used in a jaw structure for sealing tissue together with hydrojet means for transecting the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/830,372 filed on Apr. 22, 2004, which claims the benefit ofProvisional U.S. Patent Application No. 60/464,935 filed Apr. 22, 2003;is a continuation-in-part of U.S. patent application Ser. No. 10/017,582filed Dec. 7, 2001, now U.S. Pat. No. 6,669,694, which claims thebenefit of Provisional U.S. Patent Application No. 60/254,487 filed Dec.9, 2000; and is a continuation-in-part of U.S. patent application Ser.No. 10/681,625 filed Oct. 7, 2003 which claims benefit of ProvisionalU.S. Patent Application No. 60/416,622 filed Oct. 7, 2002, the contentsof which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

This invention relates to the working end of a medical instrument thatapplies energy to tissue from a fluid within a microfluidictissue-engaging surface fabricated by soft lithography means togetherwith optional superlattice cooling means that allows for very precisecontrol of energy application, for example in neurosurgery applications.

Various types of radiofrequency (Rf) and laser surgical instruments havebeen developed for delivering thermal energy to tissue, for example tocause hemostasis, to weld tissue or to cause a thermoplastic remodelingof tissue. While such prior art forms of energy delivery work well forsome applications, Rf and laser energy typically cannot cause highly“controlled” and “localized” thermal effects that are desirable inmicrosurgeries or other precision surgeries. In general, the non-linearor non-uniform characteristics of tissue affect both laser and Rf energydistributions in tissue. The objective of sealing or welding tissuerequires means for elevating the tissue temperature uniformly throughouta targeted site.

What is needed is an instrument and technique (i) that can controllablydeliver thermal energy to non-uniform tissue volumes; (i) that canshrink, seal, weld or create lesions in selected tissue volumes withoutdesiccation or charring of adjacent tissues; (iii); and (iv) that doesnot cause stray electrical current flow in tissue.

BRIEF SUMMARY OF THE INVENTION

The present invention is adapted to provide improved methods ofcontrolled thermal energy delivery to localized tissue volumes, forexample for sealing, welding or thermoplastic remodeling of tissue. Ofparticular interest, the method causes thermal effects in targetedtissue without the use of Rf current flow through the patient's body.

In general, the thermally-mediated treatment method comprises causing avapor-to-liquid phase state change in a selected media at a targetedtissue site thereby applying thermal energy substantially equal to theheat of vaporization of the selected media to said tissue site. Thethermally-mediated therapy can be delivered to tissue by suchvapor-to-liquid phase transitions, or “internal energy” releases, aboutthe working surfaces of several types of instruments for endoluminaltreatments or for soft tissue thermotherapies. FIGS. 1A and 1Billustrate the phenomena of phase transitional releases of internalenergies. Such internal energy involves energy on the molecular andatomic scale—and in polyatomic gases is directly related tointermolecular attractive forces, as well as rotational and vibrationalkinetic energy. In other words, the method of the invention exploits thephenomenon of internal energy transitions between gaseous and liquidphases that involve very large amounts of energy compared to specificheat.

It has been found that the controlled application of internal energiesin an introduced media-tissue interaction solves many of the vexingproblems associated with energy-tissue interactions in Rf, laser andultrasound modalities. The apparatus of the invention provides afluid-carrying chamber in the interior of the device or working end. Asource provides liquid media to the interior chamber wherein energy isapplied to instantly vaporize the media. In the process of theliquid-to-vapor phase transition of a saline media in the interior ofthe working end, large amounts of energy are added to overcome thecohesive forces between molecules in the liquid, and an additionalamount of energy is requires to expand the liquid 1000+ percent (PΔD)into a resulting vapor phase (see FIG. 1A). Conversely, in thevapor-to-liquid transition, such energy will be released at the phasetransitions at the targeted tissue interface. That is, the heat ofvaporization is released in tissue when the media transitioning fromgaseous phase to liquid phase wherein the random, disordered motion ofmolecules in the vapor regain cohesion to convert to a liquid media.This release of energy (defined as the capacity for doing work) relatingto intermolecular attractive forces is transformed into therapeutic heatfor a thermotherapy within a targeted body structure. Heat flow and workare both ways of transferring energy.

In FIG. 1A, the simplified visualization of internal energy is usefulfor understanding phase transition phenomena that involve internalenergy transitions between liquid and vapor phases. If heat were addedat a constant rate in FIG. 1A (graphically represented as 5 calories/gmblocks) to elevate the temperature of water through its phase change toa vapor phase, the additional energy required to achieve the phasechange (latent heat of vaporization) is represented by the large numberof 110+ blocks of energy at 100° C. in FIG. 1A. Still referring to FIG.1A, it can be easily understood that all other prior art ablationmodalities—Rf, laser, microwave and ultrasound—create energy densitiesby simply ramping up calories/gm as indicated by the temperature rangefrom 37° C. through 100° C. as in FIG. 1A. The prior art modalities makeno use of the phenomenon of phase transition energies as depicted inFIG. 1A.

FIG. 1B graphically represents a block diagram relating to energydelivery aspects of the present invention. The system provides forinsulative containment of an initial primary energy-media within aninterior chamber of an instrument's working end. The initial, ascendantenergy-media interaction delivers energy sufficient to achieve the heatof vaporization of a selected liquid media such as saline within aninterior of the instrument body. This aspect of the technology requiresan inventive energy source and controller—since energy application fromthe source to the selected media (Rf, laser, microwave etc.) must bemodulated between very large energy densities to initially surpass thelatent heat of vaporization of the media within milliseconds, andpossible subsequent lesser energy densities for maintaining the media inits vapor phase. Additionally, the energy delivery system is coupled toa pressure control system for replenishing the selected liquid phasemedia at the required rate—and optionally for controlling propagationvelocity of the vapor phase media from the working end surface of theinstrument. In use, the method of the invention comprises the controlleddeposition of a large amount of energy—the heat of vaporization as inFIG. 1A—when the vapor-to-liquid phase transition is controlled at thevapor media-tissue interface. The vapor-to-liquid phase transitiondeposits about 580 cal/gram within the targeted tissue site to performthe thermal ablation.

This new ablation modality can utilize specialized instrument workingends for several cardiovascular therapies or soft tissue ablationtreatments for tissue sealing, tissue shrinkage, tissue ablation,creation of lesions or volumetric removal of tissue. In general, theinstrument and method of the invention advantageously cause thermalablations rapidly and efficiently compared to conventional Rf energyapplication to tissue.

In one embodiment, the instrument of the invention provides a tissueengaging surface of a polymeric body that carries microfluidic channelstherein. The tissue-engaging surfaces are fabricated by soft lithographymeans to provide the fluidic channels and optional conductive materialsto function as electrodes.

In another embodiment, the instrument has a working end with asuperlattice cooling component that cooperates with the delivery ofenergy. For example, in neurosurgery, the superlattice cooling can beused to allow a brief interval of thermal energy delivery to coagulatetissue followed by practically instantaneous cooling and renaturing ofproteins in the coagulated tissue to allowing sealing and to prevent thepossibility of collateral thermal damage. At the same time, the coolingmeans insures that tissue will not stick to a jaw structure. In apreferred embodiment, the invention utilizes a thermoelectric coolingsystem as disclosed by Rama Venkatasubramanian et al. in U.S. patentapplication Ser. No. 10/265,409 (Published Application No. 20030099279published May 29, 2003) titled Phonon-blocking, electron-transmittinglow-dimensional structures, which is incorporated herein by reference.The cooling system is sometimes referred to as a PBETS device, anacronym relating to the title of the patent application. The inventors(Venkatasubramanian et al) also disclosed related technologies in U.S.Pat. No. 6,300,150 titled Thin-film thermoelectric device andfabrication method of same, which is incorporated herein by reference.

In another embodiment, the instrument provides a tissue engaging surfacewith capillary dimension channels to draw a liquid into the channelswherein an energy emitter is used to eject vapor from the open ends ofthe capillaries.

The instrument and method of the invention generate vapor phase mediathat is controllable as to volume and ejection pressure to provide anot-to-exceed temperature level that prevents desiccation, eschar, smokeand tissue sticking.

The instrument and method of the invention advantageously createsthermal effects in a targeted tissue volume with substantiallycontrolled lateral margins between the treated tissue and untreatedtissue.

Additional advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Various embodiments of the present invention will be discussed withreference to the appended drawings. These drawings depict onlyillustrative embodiments of the invention and are not to be consideredlimiting of its scope.

FIG. 1A is a graphical depiction of the quantity of energy needed toachieve the heat of vaporization of water.

FIG. 1B is a diagram of phase change energy release that underlies onemethod of the invention.

FIG. 2A is a perspective view of the working end of an exemplary Type“A” probe of the present invention with an openable-closeable tissueengaging structure in a first open position.

FIG. 2B is a perspective view similar to FIG. 2A probe of the presentinvention in a second closed position.

FIG. 3 is a cut-away view of the working end of FIGS. 2A-2B.

FIG. 4 is a perspective view of the working end of FIG. 3 capturing anexemplary tissue volume.

FIGS. 5-6 are sectional schematic views of working end of FIG. 3depicting, in sequence, the steps of a method of the present inventionto seal or weld a targeted tissue volume, FIG. 5 illustrating thepressurized delivery of a liquid media to an interior channel, and FIG.6 depicting an electrical discharge that causes a liquid-to-gas phasechange as well as the ejection of the vapor media into the targetedtissue to cause a thermal weld.

FIG. 7 is a perspective view of an alternative working end of thepresent invention.

FIG. 8 is a sectional view of the working end of FIG. 7 showing amicrochannel structure.

FIG. 9 is a greatly enlarged sectional view of the microchannelstructure of FIG. 8 depicting the electrode arrangement carried therein.

FIG. 10 is a schematic sectional view of an alternative working end witha helical electrode arrangement in the interior chamber.

FIG. 11 illustrates a method of the invention in treating a blood vesseldisorder with the device of FIG. 10.

FIG. 12 illustrates a probe-type medical instrument that carries atissue-engaging surface comprising a polymeric monolith withmicrofluidic interior channels that carry an energy-delivery fluidmedia.

FIG. 13 illustrates an enlarged view of the working end of theinstrument of FIG. 12.

FIG. 14 is a view of a forceps-type instrument that carries atissue-engaging surface similar to that of FIGS. 12 and 13 comprising apolymeric monolith with microfluidic channels for applying energy totissue.

FIG. 15 is a greatly enlarged cut-away view of the tissue-engagingsurface of FIGS. 13 and 14 with microfluidic interior channels thatcarry an energy-delivery vapor media adapted for release from outlets inthe engagement surface.

FIG. 16 is a cut-away view of an alternative tissue-engaging surfacesimilar to FIG. 15 with microfluidic interior channels that carry aflowing conductive liquid media for coupling energy to tissue in abi-polar mode.

FIGS. 17A-17B illustrate the tissue-engaging surface of FIG. 16 withelectrical circuitry adapted to alter the polarity of groups of fluidicchannels that each carry a flowing conductive liquid media.

FIGS. 18A-18B are view of exemplary tissue-engaging surfaces thatincludes first surface portions of a superlattice cooling structure andsecond surface portions of a thermal-energy emitter.

FIG. 19 is a view of a neurosurgery forceps jaw that includes asuperlattice cooling structure together with a bipolar electrode.

FIG. 20 is a cut-away view of an alternative tissue-engaging surfacehaving microfluidic channels that utilize a capillary effect to draw aliquid media into the channels wherein electrical energy causes aliquid-to-vapor conversion and ejection of the vapor media from theengagement surface.

FIG. 21 illustrates a jaw structure that carries engagement surfaceswith soft lithography microfabricated energy delivery surfaces of theinvention together with very high pressure water jetting means fortransecting sealed tissue.

DETAILED DESCRIPTION OF THE INVENTION

1. Type “A” Thermotherapy Instrument.

Referring to FIGS. 2A, 2B and 3, the working end 10 of a Type “A” system5 of the present invention is shown that is adapted for endoscopicprocedures in which a tissue volume T targeted for treatment (athermoplasty) can be captured by a loop structure. The working end 10comprises a body 11 of insulator material (see FIG. 3) coupled to thedistal end of introducer member 12 extending along axis 15. In thisexemplary embodiment, the working end 10 has a generally cylindricalcross-section and is made of any suitable material such as plastic,ceramic, glass, metal or a combination thereof. The working end 10 issubstantially small in diameter (e.g., 2 mm to 5 mm) and in thisembodiment is coupled to an elongate flexible introducer member 12 tocooperate with a working channel in an endoscope. Alternatively, theworking end 10 may be coupled to a rigid shaft member having a suitable1 mm to 5 mm or larger diameter to cooperate with a trocar sleeve foruse in endoscopic or microsurgical procedures. A proximal handle portion14 of the instrument indicated by the block diagram of FIG. A carriesthe various actuator mechanisms known in the art for actuatingcomponents of the instrument.

In FIGS. 2A, 2B and 3, it can be seen that the working end 10 carries anopenable and closeable structure for capturing tissue between a firsttissue-engaging surface 20A and a second tissue-engaging surface 20B. Inthis exemplary embodiment, the working end 10 and first tissue-engagingsurface 20A comprises a non-moving component indicated at 22A that isdefined by the exposed distal end of body 11 of working end 10. Thesecond tissue-engaging surface 20B is carried in a moving component thatcomprises a flexible loop structure indicated at 22B.

The second moving component or flexible loop 22B is actuatable by aslidable portion 24 a of the loop that extends through a slot 25 in theworking end to an actuator in the handle portion 14 as is known in theart (see FIG. 3). The other end 24 b of the loop structure 22B is fixedin body 11. While such an in-line (or axial) flexible slidable member ispreferred as the tissue-capturing mechanism for a small diameterflexible catheter-type instrument, it should be appreciated that anyopenable and closable jaw structure known in the art falls within thescope of the invention, including forms of paired jaws with cam-surfaceactuation or conventional pin-type hinges and actuator mechanisms. FIG.2A illustrates the first and second tissue-engaging surfaces 20A and 20Bin a first spaced apart or open position. FIG. 2B shows the first andsecond surfaces 20A and 20B moved toward a second closed position.

Now turning to the fluid-to-gas energy delivery means of the invention,referring to FIG. 3, it can be seen that the insulated or non-conductivebody 11 of working end 10 carries an interior chamber indicated at 30communicating with lumen 33 that are together adapted for delivery andtransient confinement of a fluid media M that flows into chamber 30. Thechamber 30 communicates via lumen 33 with a fluid media source 35 thatmay be remote from the device, or a fluid reservoir (coupled to a remotepressure source) carried within introducer 12 or carried within a handleportion 14. The term fluid or flowable media source 35 is defined toinclude a positive pressure inflow system which may be a syringe, anelevated remote fluid sac that relies on gravity, or any suitablepump-type pressure means known in the art. The fluid delivery lumen 33transitions to chamber 30 at proximal end portion 34 a thereof. Thedistal end portion 34 b of chamber 30 has a reduced cross-section to(optionally) function as a jet or nozzle indicated at 38.

Of particular interest, still referring to FIG. 3, paired electrodeelements 40A and 40B with exposed surfaces and that are spaced apart insurface 42 of the interior fluid confinement chamber 30. In thisexemplary embodiment, the electrode elements 40A and 40B comprisecircumferential exposed surfaces of a conductive material positioned atopposing proximal and distal ends of interior chamber 30. It should beappreciated that the method of the invention of may utilize any suitableconfiguration of spaced apart electrodes (e.g., spaces apart helicalelectrode elements or porous electrodes) about at least one confinementchamber 30 or lumen portion. Alternatively, each electrode can be asingular projecting element that projects into the chamber. Theexemplary embodiment of FIG. 3 shows an elongate chamber having an axialdimension indicated at A and diameter or cross-section indicated at B.The axial dimension may range from about 0.1 mm to 20.0 mm and may besingular or plural as described below. The diameter B may range frommicron dimensions (e.g., 0.5 μm) for miniaturized instruments to alarger dimension (e.g., 5.0 mm) for larger instruments for causing thethermally induced fluid-to-gas transformation required to enable thenovel phase change energy-tissue interaction of the invention. Theelectrodes are of any suitable material such as aluminum, stainlesssteel, nickel titanium, platinum, gold, or copper. Each electrodesurface preferably has a toothed surface texture indicated at 43 thatincludes hatching, projecting elements or surface asperities for betterdelivering high energy densities in the fluid proximate to theelectrode. The electrical current to the working end 10 may be switchedon and off by a foot pedal or any other suitable means such as a switchin handle 14.

FIG. 3 further shows that a preferred shape is formed into thetissue-engaging surface 20A to better perform the method of fusingtissue. As can be seen in FIGS. 2B and 3, the first tissue-engagingsurface 20A is generally concave so as to be adapted to receive agreater tissue volume in the central portion of surface 20A. The secondtissue-engaging surface 20B is flexible and naturally will be concave inthe distal or opposite direction when tissue is engaged between surfaces20A and 20B. This preferred shape structure allows for controllablecompression of the thick targeted tissue volumes T centrally exposed tothe energy delivery means and helps prevent conductance of thermaleffects to collateral tissue regions CT (see FIG. 4) and as will bedescribed in greater detail below.

FIGS. 2A and 3 show that first tissue-engaging surface 20A defines anopen structure of at least one aperture or passageway indicated at 45that allows vapor pass therethrough. The apertures 45 may have anycross-sectional shape and linear or angular route through surface 20Awith a sectional dimension C in this embodiment ranging upwards frommicron dimensions (e.g., 0.5 μm) to about 2.0 mm in a large surface 20A.The exemplary embodiment of FIG. 3 has an expanding cross-sectiontransition chamber 47 proximate to the aperture grid that transitionsbetween the distal end 34 b of chamber 30 and the apertures 45. However,it should be appreciated that such a transition chamber 47 is optionaland the terminal portion of chamber 30 may directly exit into aplurality of passageways that each communicate with an aperture 45 inthe grid of the first engaging surface 20A. In a preferred embodiment,the second tissue-engaging surface 20B defines (optionally) a grid ofapertures indicated at 50 that pass through the loop 22B. Theseapertures 50 may be any suitable dimension (cf. apertures 45) and areadapted to generally oppose the first tissue-engaging surface 20A whenthe surfaces 20A and 20B are in the second closed position, as shown inFIG. 2B.

The electrodes 40A and 40B of working end 10 have opposing polaritiesand are coupled to electrical generator 55. FIG. 3 showscurrent-carrying wire leads 58 a and 58 b that are coupled to electrodes40A and 40B and extend to electrical source 55 and controller 60. In apreferred embodiment of the invention, either tissue-engaging surfaceoptionally includes a sensor 62 (or sensor array) that is in contactwith the targeted tissue surface (see FIG. 2A). Such a sensor, forexample a thermocouple known in the art, can measure temperature at thesurface of the captured tissue. The sensor is coupled to controller 60by a lead (not shown) and can be used to modulate or terminate powerdelivery as will be described next in the method of the invention.

Operation and use of the working end of FIGS. 2A, 2B and 3 in performinga method of treating tissue can be briefly described as follows, forexample in an endoscopic polyp removal procedure. As can be understoodfrom FIG. 4, the working end 10 is carried by an elongate catheter-typemember 12 that is introduced through a working channel 70 of anendoscope 72 to a working space. In this case, the tissue T targeted forsealing is a medial portion 78 of a polyp 80 in a colon 82. It can beeasily understood that the slidable movement of the loop member 22B cancapture the polyp 80 in the device as shown in FIG. 4 after beinglassoed. The objective of the tissue treatment is to seal the medialportion of the polyp with the inventive thermotherapy. Thereafter,utilize a separate cutting instrument is used to cut through the sealedportion, and the excised polyp is retrieved for biopsy purposes.

Now turning to FIGS. 5 and 6, two sequential schematic views of theworking end engaging tissue T are provided to illustrate theenergy-tissue interaction caused by the method of the invention. FIG. 5depicts an initial step of the method wherein the operator sends asignal to the controller 60 to delivery fluid media M (e.g., salinesolution or sterile water) through lumen 33 into chamber 30. FIG. 6depicts the next step of the method wherein the controller delivers anintense discharge of electrical energy to the paired electrode elements40A and 40B within chamber 30 indicated by electric arc or electricfield EF. The electrical discharge provides energy exceeding the heat ofvaporization of the contained fluid volume. The explosive vaporizationof fluid media M (of FIG. 5) into a vapor or gas media is indicated atM′ in FIG. 6. The greatly increased volume of gas media M′ results inthe gas being ejected from chamber 30 at high velocity through apertures45 of surface 20A into the targeted tissue T. The liquid to gasconversion caused by the electrical discharge also heats the gas mediaM′ to about 100° C. to deliver thermal effects into tissue T, or eventhrough the targeted tissue T, as indicated graphically by the shadedregions of gas flow in FIG. 6. The fluid source and its pressure or pumpmechanism can provide any desired level of vapor ejection pressure.Depending on the character of the introduced liquid media, the media isaltered from a first lesser temperature to a second greater temperaturein the range of 100° C. or higher depending on pressure. The ejection ofvapor media M′ will uniformly elevate the temperature of the engagedtissue to the desired range of about 65° C. to 100° C. very rapidly tocause hydrothermal denaturation of proteins in the tissue, and to causeoptimal fluid intermixing of tissue constituents that will result in aneffective seal. In effect, the vapor-to-liquid phase transition of theejected media M′ will deposit heat equal to the heat of vaporization inthe tissue. At the same time, as the heat of vaporization of media M′ isabsorbed by water in the targeted tissue, the media converts back to aliquid thus hydrating the targeted tissue T. It is believed that suchprotein denaturation by hydrothermal effects differentiates this methodof tissue sealing or fusion from all other forms of energy delivery,such as radiofrequency energy delivery. All other forms of energydelivery vaporize intra- and extracellular fluids and cause tissuedesiccation, dehydration or charring which is undesirable for theintermixing of denatured tissue constituents into a proteinaceousamalgam.

The above electrical energy deliver step is repeated at a highrepetition rate to cause a pulsed form of thermal energy delivery in theengaged tissue. The fluid media M inflow may be continuous or pulsed tosubstantially fill chamber 30 before an electrical discharge is causedtherein. The repetition rate of electrical discharges may be from about1 Hz to 1000 Hz. More preferably, the repetition rate is from about 10Hz to 200 Hz. The selected repetition rate preferably provides aninterval between electrical discharges that allows for thermalrelaxation of tissue, that may range from about 10 ms to 500 ms. Theelectrical source or voltage source 55 may provide a voltage rangingbetween about 100 volts and 10,000 volts to cause instant vaporizationof the volume of fluid media M captured between the electrode elements40A and 40B. After a selected time interval of such energy applicationto tissue T, that may range from about 1 second to 30 seconds, andpreferably from about 5 to 20 seconds, the engaged tissue will becontain a core region in which the tissue constituents are denatured andintermixed under relatively high compression between surfaces 20A and20B. Upon disengagement and cooling of the targeted tissue T, thetreated tissue will be fused or welded. Over time, the body's woundhealing response will reconstitute the treated tissue with an intermixedcollagenous volume or scar-like tissue.

An optional method of controlling the repetition rate of electricaldischarges comprises the measurement of electrical characteristics ofmedia M within the chamber 30 to insure that the chamber is filled withthe fluid media at time of the electrical discharge. The electricalmeasurement then would send a control signal to the controller 60 tocause each electrical discharge. For example, the liquid media M can beprovided with selected conductive compositions in solution therein. Thecontroller 60 then can send a weak electrical current between the pairedelectrodes 40A and 40B and thereafter sense the change in an impedancelevel between the electrodes as the chamber 30 is filled with fluid togenerate the control signal.

Referring to FIG. 7, a working end 210 of an alternative instrument 205of the present invention is depicted. The phase transitional energydelivery aspects of the invention are the same as described above. Theinstrument 205 differs in that it utilizes significantly reduceddimensions (or micronization) of features in the working end 210. Moreparticularly, a fluid media source 235A and pressure control system 235Bare adapted to provide pressurized flows of liquid media M through theintroducer body 211 and thereafter into microchannel body or structureindicated at 215 (see FIG. 8). The microchannel or microporous bodydefines therein plurality of small diameter fluid passageways ormicrochannel portions 216 (collectively). The microchannel body 215 alsocan be a microporous trabecular material to provide open-cell flowpassageways therethrough.

In FIG. 8, it can be seen that the microchannel body 215 comprises astructure of an electrically insulative material (or a conductivematerial with an insulative coating) that defines open flow passagewaysor channels 216 therethrough that have open terminations or ports 218 inthe working surface 220. At an interior of the microchannel body 215, anintermediate region of the open flow channels 216 is exposed to firstand second electrode elements 240A and 240B. The electrode elements 240Aand 240B can be formed in a plates or layers of channeled material ortrabecular material that extends transverse to passageways 216. Thus,the channels are exposed to surfaces of the electrode elements 240A and240B interior of the working surface 220 that interfaces with thetargeted tissue T. As depicted in FIG. 9, electrical energy is appliedbetween the electrodes to cause vaporization of the inflowing liquidmedia M which is converted to a vapor media M′ within the interior ofthe channels 216 for ejection from the working surface 220 to interactwith tissue as described above.

A working end similar to that of FIGS. 7-8 can be used in variousthermotherapy procedures. For example, a rigid probe can be used inorthopedic procedures to cause hydrothermal shrinkage of collagen, forexample in a spinal disc, or a joint capsule to stabilize the joint (seeU.S. patent application Ser. No. 09/049,711 filed Mar. 27, 1998,incorporated herein by this reference). In an arthroscopic procedure,the working end is painted across a targeted tissue site in a jointcapsule to shrink tissue. In another procedure, the working end may bestabilized against any collagenous tissue to heat and shrink collagen ina targeted tissue such as a herniated disc. In another procedure, theworking end can be painted across the surface of a patient's esophagusto ablate abnormal cells to treat a disorder known as Barrett'sesophagus. As described previously, the thermal energy delivery means ofthe invention preferably uses an electrical energy source and spacedapart electrodes for flash vaporization of a liquid media. It should beappreciated that a resistive element coupled to an electrical sourcealso can be used. For example, a resistive element can fabricated out ofany suitable material such a tungsten alloy in a helical, tubular or amicroporous form that allows fluid flow therethrough.

Now referring to FIGS. 10 and 11, another embodiment of instrumentworking end 300 is shown in schematic sectional view. The previousdevices were shown and optimized for having a working surface thatengages tissue, and for controlling and limiting thermal effects inengaged tissue. In the embodiment of FIG. 10, the working end is adaptedfor controlled application of energy by means of phase change energyrelease in an endovascular application, or in media within or aboutother body lumens, ducts and the like.

FIG. 10 illustrates the working end 300 of a member or catheter body 305that is dimensioned for introduction into a patient's vasculature orother body lumen. The diameter of body 305 can range from about 1 Fr. to6 Fr. or more. The working end 300 typically is carried at the distalend of a flexible catheter but may also be carried at the distal end ofa more rigid introducer member. In a rigid member, the working end alsocan be sharp for penetrating into any soft tissue (e.g. a fibroid,breast lesion or other organ such as a prostate) or into the lumen of avessel.

The working end 300 of FIG. 10 has an interior chamber 310 again incommunication with fluid media inflow source 335A and pressure controlsystem 335B. The interior chamber 310 carries opposing polarityelectrodes 315A and 315B as thermal energy emitters. The distal terminusor working surface 320 of the catheter has media entrance port 322therein. In this embodiment, the electrodes 315A and 315B are spacedapart, indicated with (+) and (−) polarities coupled to electricalsource 355, and are of a flexible material and configured in anintertwined helical configuration to provide a substantially largesurface area for exposure to inflowing fluid media M. The electrodes canextend axially from about 1 mm to 50 mm and are spaced well inward, forexample from 1 mm to 100 mm from the distal working surface 320. Thistype of electrode arrangement will enhance energy delivery to the liquidmedia M to allow effective continuous vaporization thereof. The lumen orchamber portion between electrodes 315A and 315B allows for focusedenergy application to create the desired energy density in the inflowingmedia M to cause its immediate vaporization. The vapor is thenpropagated from the working surface 320 via port 322 to interact withthe endoluminal media. It should be appreciated that the instrument mayhave a plurality of media entrance ports 322 in the working surface, oradditionally the radially outward surfaces of the catheter.

In the system embodiment of FIG. 10, the electrodes 315A and 315B arecoupled to electrical source 355 by leads 356 a and 356 b. The workingend 300 also is coupled to fluid media source 335A that carriespressurization means of any suitable type together with a pressurecontrol system indicated at 335B.

In FIG. 11, the method of the invention is shown graphically wherein thedistal end 300 is introduced into vasculature for the purpose ofcreating thermal effects in the vessel walls 360. In one targetedendovascular procedure, as depicted in FIG. 11, the objective is toapply controlled thermal energy to tissue to shrink and/or damage vesselwalls to treat varicose veins. Most endothelial-lined structures of thebody, such as blood vessel and other ducts, have substantially collagencores for specific functional purposes. Intermolecular cross-linksprovide collagen connective tissue with unique physical properties suchas high tensile strength and substantial elasticity. A well-recognizedproperty of collagen relates to the shrinkage of collagen fibers whenelevated in temperature to the range 60° to 80° C. Temperature elevationruptures the collagen ultrastructural stabilizing cross-links, andresults in immediate contraction in the fibers to about one-third oftheir original longitudinal dimension. At the same time, the caliber ofthe individual collagen fibers increases without changing the structuralintegrity of the connective tissue.

As represented in FIG. 11, the delivery of energy from the electrodes315A and 315B to an inflow of liquid media M, such as any salinesolution, will cause its instant vaporization and the expansion of thevapor (in addition to pressure from pressure source 335B) will causehigh pressure gradients to propagate the heated vapor from port 322 tointeract with endovascular media. The pressurized fluid media source335A and pressure control subsystem 335B also can be adapted to create apressure gradient, or enhance the pressure gradients caused by vaporexpansion, to controllably eject the heated vapor from the workingsurface 320. As depicted in FIG. 11, the vaporized media M′ depositsenergy to the vessel walls in the vapor to liquid phase change energyrelease. The vaporized media is at about 100° C. as it crosses theinterface between the working surface 320 and blood and will push theblood distally while at the same time causing the desired thermaleffects in the vessel wall 360.

As shown in FIG. 11, the collagen in the vessel walls will shrink and/ordenature (along with other proteins) to thereby collapse the vessel.This means of applying thermal energy to vessel walls can controllablyshrink, collapse and occlude the vessel lumen to terminate blood flowtherethrough, and offers substantial advantages over alternativeprocedures. Vein stripping is a much more invasive treatment. Rf closureof varicose veins is known in the art. Typically, a catheter device ismoved to drag Rf electrodes along the vessel walls to apply Rf energy todamage the vessel walls by means of causing ohmic heating. Such Rf ohmicheating causes several undesirable effects, such as (i) creating highpeak electrode temperatures (up to several hundred degrees C.) that candamage nerves extending along the vessel's exterior, (ii) causingnon-uniform thermal effects about valves making vessel closureincomplete, and (iii) causing vessel perforations as the catheterworking end is dragged along the vessel walls. In contrast, the energydelivery system of the invention utilizes the heat of a vapor media thatcannot exceed about 100° C. (or slightly higher depending on pressure)to apply energy to the vessel walls. This method substantially preventsheat from being propagated heat outwardly by conduction—thus preventingdamage to nerves. There is no possibility of causing ohmic heating innerves, since a principal advantage of the invention is the applicationof therapeutic heat entirely without electrical current flow in tissue.Further, the vapor and its heat content can apply substantially uniformthermal effects about valves since the heat transfer mechanism isthrough a vapor that contacts all vessel wall surfaces—and is not anelectrode that is dragged along the vessel wall. In one method of theinvention, the vapor M′ can be propagated from working end 300 whilemaintained in a single location. Thus, the system of the invention maynot require the navigation of the catheter member 305 through tortuousvessels. Alternatively, the working end 300 may be translated along thelumen as energy is applied by means of vapor-to-liquid energy release.

Another advantage of the invention is that the system propagates atherapeutic vapor media M′ from the working surface 320 that can beimaged using conventional ultrasound imaging systems. This will providean advantage over other heat transfer mechanisms, such as ohmic heating,that cannot be directly imaged with ultrasound.

Another embodiment of the invention is shown in FIGS. 12-15 and isadapted for enhancing energy application to tissue by phase changeenergy releases in more precise tissue treatments, or to treat onlysurface layers of tissue. For example, the inventive system can becarried in a probe working end as in FIGS. 12 and 13 for applyingthermal energy to a limited depth in a skin treatment. Alternatively,the system can be used in forceps as in FIG. 14 that is suited forneurosurgery and other precise surgeries for coagulating tissue whileinsuring that tissue sticking cannot occur.

In general, this embodiment includes (i) a polymeric monolith withmicrofluidic circuitry at an interior of the engagement surface forcontrolling the delivery of energy from the fluid to the engaged tissue;(ii) optional contemporaneous cooling of the microfluidic circuitry andengagement surface for controlling thermal effects in tissue; and (iii)optional coupling of additional Rf energy to the fluid mediacontemporaneous with ejection from the engagement surface to enhanceenergy application at the tissue interface.

FIGS. 12 and 13 illustrate a probe-type instrument 400A corresponding tothe invention that is adapted for micro-scale energy delivery to tissue,such as a patient's skin. More in particular, the instrument 400 has ahandle portion 402 and extension portion 404 that extends to working end405. The working end carries a polymer microfluidic body 410 with anengagement surface 415 for engaging tissue. The engagement surface 415can be flat or curved and have any suitable dimension. Its method of usewill be described in more detail below.

FIG. 14 illustrates a forceps-type instrument 400B having aconfiguration that is common in neurosurgery instruments. The instrumentof FIG. 14 has first and second tines or jaw elements 416 a and 416 bwherein at least one jaw carries a microfluidic body 410 having anengagement surface 415 for engaging tissue. It should be appreciatedthat the jaws can have any suitable dimensions, shape and form.

Now referring to FIG. 15, a greatly enlarged view of body 410 andengagement surface 415 of FIGS. 13 and 14 is shown. In one aspect of theinvention, the microfabricated body 410 carries microfluidic channels420 adapted to carry a fluid media 422 from a pressurized media source425 as described in previous embodiments. The media 422 is carried fromsource 425 by at least one inflow lumen 426A to the microfluidicchannels 420 in body 410 (see FIGS. 12-14). In some embodiments, anoutflow lumen 426B is provided in the instrument body to carry at leastpart of fluid 422 to a collection reservoir 428. Alternatively, thefluid 422 can move in a looped flow arrangement to return to the fluidmedia source 425 (see FIGS. 12-14). The engagement surface can besmooth, textured or having surface features for gripping tissue. In theembodiment of FIG. 15, the surface is provided with grooves 429 thatprovide a grip surface that is useful in jaw structures as in FIG. 14.The microfluidic channels have a mean cross section of less than 1 mm.Preferably, the channels have a mean cross section of less than 0.5 mm.The channels 420 can have any cross-sectional shape, such as rectangularor round that is dependent on the means of microfabrication.

FIG. 15 depicts one exemplary embodiment of engagement surface 415 thatfurther carries a large number of open terminations or ports 430 in thesurface for permitting propagation of vapor phase media 422 from theports 430. In this aspect of the invention, the system applies energy totissue as described in the earlier embodiments (see FIGS. 5-10). Themicrofluidic channels 420 extend in any suitable pattern or circuitryfrom at least one inflow lumen 426A. The system can be designed to eject100% of the vapor phase media from the ports 430 for thermal interactionwith tissue. In a preferred embodiment, the microfluidic channels 420extend across the engagement surface 415 and then communicate with atleast one outflow lumen 426B (see FIGS. 12 and 13). In the embodiment ofFIG. 15, the ejection of vapor media through ports 430 then can bemodulated by both inflow pressures and by suction from the optionalnegative pressure source 435 coupled to the outflow lumen 426B (seeFIGS. 12 and 13). The flow channels 420 further can have an increase incross-sectional dimension proximate the surface 415 or proximate eachport 430 to allow for lesser containing pressure on the vapor to assistin its vapor to liquid phase transition.

In another embodiment, the engagement surface can have other suctionports (not shown) that are independent of the fluidic channels 420 forsuctioning tissue into contact with the engagement surface 415. Asuction source can be coupled to such suction ports.

In the embodiment of FIGS. 13 and 14, the system includes an electricalsource 355 and fluid media source 335A as described above for convertinga liquid media to a vapor media in a handle or extension portion, 402 or404, of the instrument. The system further has a fluid pressure controlsystem 335B for controlling the media inflow pressures as in theembodiment of FIGS. 10-12.

Of particular interest, the microfabricated body 410 can be of anelastomer or other suitable polymer of any suitable modulus and can bemade according to techniques based on replication molding wherein thepolymer is patterned by curing in a micromachined mold. A number ofsuitable microfabrication processes are termed soft lithography. Theterm multilayer soft lithography combines soft lithography with thecapability to bond multiple patterned layers of polymers to form amonolith with fluid and electric circuitry therein. A multilayer body410 as in FIGS. 15 and 16 can be constructed by bonding layers 438 of aselected polymer, each layer of which is separately cast from amicromachined mold. An elastomer bonding system can be a two componentaddition-cure of silicone rubber typically.

The scope of the invention encompasses the use of multilayer softlithography microfabrication techniques for making thermal vapordelivery surfaces and electrosurgical engagement surfaces, wherein suchenergy delivery surfaces consist of multiple layers 438 fabricated ofsoft materials with microfluidic circuitry therein as well as electricalconductor components.

In an optional embodiment illustrated in FIG. 16, as will be furtherdescribed below, the microfluidic circuitry further carries electrodes440A and 440B for coupling electrical energy to a conductive fluid 422that flows within the microchannels 420. Multilayer soft lithographictechniques for microfluidics are described, in general, in the followingreferences which are incorporated herein by this reference: Marc A.Unger, Hou-Pu Chou, Todd Thorsen, Axel Scherer, and Stephen R. Quake,“Monolithic Microfabricated Valves and Pumps by Multilayer SoftLithography”(http://thebigone.caltech.edu/quake/publications/scienceapr0-0.pdf) andYounan Xia and George M. Whitesides, “Soft Lithography”,(http://web.mit.edu/10.491/softlithographyreview.pdf).

In any embodiment of polymer body 410, as described above, the layers438 can be microfabricated using soft lithography techniques to providean open or channeled interior structure to allow fluid flowstherethrough. The use of resilient polymers (e.g., silicone) ispreferred and the more particular microfabrication techniques includeany of the following. For example, microtransfer molding is used whereina transparent, elastomeric polydimethylsiloxane (PDMS) stamp haspatterned relief on its surface to generate features in the polymer. ThePDMS stamp is filled with a prepolymer or ceramic precursor and placedon a substrate. The material is cured and the stamp is removed. Thetechnique generates features as small as 250 nm and is able to generatemultilayer body 410 as in FIG. 15. Replica molding is a similar processwherein a PDMS stamp is cast against a conventionally patterned master.A polyurethane or other polymer is then molded against the secondaryPDMS master. In this way, multiple copies can be made without damagingthe original master. The technique can replicate features as small as 30nm. Another process is known as micromolding in capillaries (MIMIC)wherein continuous channels are formed when a PDMS stamp is brought intoconformal contact with a solid substrate. Then, capillary action fillsthe channels with a polymer precursor. The polymer is cured and thestamp is removed. MIMIC can generate features down to 1 μm in size.Solvent-assisted microcontact molding (SAMIM) is also known wherein asmall amount of solvent is spread on a patterned PDMS stamp and thestamp is placed on a polymer, such as photoresist. The solvent swellsthe polymer and causes it to expand to fill the surface relief of thestamp. Features as small as 60 nm have been produced. A background onmicrofabrication can be found in Xia and Whitesides, Annu. Rev. Mater.Sci. 1998 28:153-84 at p. 170 FIG. 7 d (the Xia and Whitesides articleincorporated herein by reference). In any embodiment of polymer body410, the polymer can have a “surface modification” to enhance fluidflows therethrough, and at the exterior surface to prevent thepossibility of adherence of body materials to the surfaces. For example,the channels can have ultrahydrophobic surfaces for enabling fluidflows, and the fluids or surfaces can carry any surfactant.

In a working end embodiment that is particularly adapted formicrosurgery, as in the forceps of FIG. 14, the microfluidic body 410with engagement surface 415 is substantially thin and is coupled tosuperlattice thermoelectric cooling means indicated at 450. Thus, thescope of the invention extends to two complementary novel structures andcomponents: (i) bipolar microfluidic, flowable electrodes, and (ii) asuperlattice cooling structure. The components will be described inorder.

FIGS. 16 and 17A-17B illustrate the microfluidic body 410 with channels420 that carry a flowing conductive fluid 422 such as hypertonic saline.The fluid 422 is delivered in a liquid form to the forceps schematicallyshown in FIG. 14. The fluid remains in a liquid state as it cyclesthrough channels 420 of the engagement surface 410 as in FIG. 16. Themicrofluidic body 410 can be adapted to delivery energy in either amonopolar or bipolar mode. In a monopolar mode, radiofrequency energy iscoupled to the flowing fluid 422 by an active electrode arrangementhaving a single polarity, wherein the targeted tissue is treated when anelectrical circuit is completed with a ground pad comprising a largearea electrode coupled to the patient at a location remote from thetargeted tissue. In a bipolar mode, radiofrequency energy is coupled toflowing fluid 422 by first and second opposing polarity electrodes 440Aand 440B in different channels 420, or different groups of channels (seeFIG. 16).

In FIG. 16, the polymeric body 410 carries electrodes 440A and 440Bhaving exposed surfaces in the interior of channels 420 for couplingelectrical energy to the conductive fluid 422. The surface layer 452 ofpolymeric material overlying channels 420 is substantially thin andallows from capacitive coupling of electrical energy to engaged tissue.The polymer is selected from a class of material known in the art thatoptimizes the delivery of electrical energy therethrough, wherein thepolymer has limited capacitance. The interior regions 454 of polymericmaterial between channels 420 has a greater dimension than the surfacelayer 452 to prevent substantial current flow between the channels atthe interior of body 410. Also, the interior layer 456 that carries thechannels can be microfabricated of a different substantially insulativepolymer to prevent current flows in the interior of body 410 between theopposing polarity channels, indicated with (+) and (−) signs.

In FIG. 16, the body 410 is illustrated in a bipolar configuration withelectrodes 440A and 440B comprising a microfabricated metal layer or aconductively doped polymer. The electrodes 440A and 440B alternativelycan comprise conductive wires inserted into the channels or can be aconductive coating fabricated into the channel walls. Soft lithographymethods also can deposit conductive layers or conductive polymers toprovide the electrode functionality of the invention. Alternative meansfor fabricating channels with conductive coatings are described in thefollowing patents to W. Hoffman et al., which are incorporated herein byreference: U.S. Pat. Nos. 6,113,722; 6,458,231; 6,194,066; 6,588,613;6,059,011; 5,352,512; 5,298,298; and 5,011,566.

FIGS. 17A-17B illustrate the microfluidic body 410 as in FIG. 16 withelectrical circuitry for altering the polarity of electrodes to providesa first polarity to a first group of fluidic channels (indicated as (+)positive pole) and a provides the second opposing polarity to a secondgroup of fluidic channels (indicated as (−) negative pole). By thismeans, the depth of ohmic heating in tissue can be adjusted as is knownin the art. In a preferred embodiment, each conductive region orelectrode is coupled to a controller and multiplexing system to allowbipolar energy application within engaged tissue between selectedindividual electrodes having transient opposing polarities, or any firstpolarity set of electrodes and fluidic channels 420 that cooperate withany set of second polarity electrodes and channels. The system can haveindependent feedback control based on impedance or temperature for eachactivated set of electrodes. In this embodiment, the polymer layeroverlying the channel also can be microporous or macroporous to allowthe conductive fluid 422 to seep through this fluid permeable layer todirectly couple electrical energy to the engaged tissue.

Now turning to the superlattice cooling component 450 of the invention,it can be seen in FIGS. 13, 14 and 16 that the superlattice componentcan be carried interior of body 410 and engagement surface 415. Asdescribed above, one preferred nanolattice cooling system was disclosedby Rama Venkatasubramanian et al. in U.S. patent application Ser. No.10/265,409 (Published Application No. 20030099279 published May 29,2003) which is incorporated herein by reference. For convenience, thisclass of thin, high performance thermoelectric device is referred toherein for convenience as a superlattice cooling device.

Superlattice cooling devices provide substantial performanceimprovements over conventional thermoelectric structures, also known asPeltier devices. It has been reported that superlattice thermoelectricmaterial having a surface dimension of about 1 cm.sup.2 can provide 700watts of cooling under a nominal temperature gradient. This wouldtranslate into an efficiency at least double that of conventionalthermoelectric devices. The use of a superlattice cooling device in asurgical instrument further provides the advantage of wafer-scalabilityand the use of known processes for fabrication. The author firstdisclosed the use of thermoelectric cooling devices in a thermal-energydelivery jaw structure in U.S. Pat. No. 6,099,251 issued Aug. 8, 2000(see Col. 21, lines 38-52).

In a typical embodiment, the thin-film superlattice cooling structurecomprises a stack of at least 10 alternating thin semiconductor layers.More preferably, the superlattice structure includes at least 100alternating layers, and can comprise 500 or more such nanoscale layers.In one embodiment, the thin film superlattice structure comprisesalternating stacks of thin film layers of bismuth telluride and antimonytelluride. The thin film superlattice structure thus comprises a circuitincluding a plurality of thin film layers of at least two dissimilarconductors wherein current propagates heat toward one end of the circuitthereby cooling the end of the circuit coupled to the energy-emittingsurface. The superlattice cooling structures are coupled to anelectrical source by independent circuitry, and can also be coupled witha control system to operate in a selected sequence with thermal energydelivery.

Referring to FIGS. 18A-18B, the scope of the invention extends to asurgical energy-emitting surface 465 for applying energy to tissuewherein the superlattice cooling structure 450 is interior of theenergy-emitting surface and/or adjacent to the energy-emitting surfacefor engaging and cooling tissue. A tissue-engaging surface can include afirst surface portion 470 of a thermal energy emitter and second surfaceportion 450 of the superlattice cooling device as in FIGS. 18A and 18B.The first and second surface portions 470 and 450 can be provided in anysuitable pattern. A working end as in FIGS. 18A and 18B can be used fortreating skin, for example in cosmetic treatments for shrinking collagenor for damaging or stimulating subsurface tissues to thereby causecollagen formation. The system can deliver a burst of thermal energyfollowed by a surface cooling to localize heat at a selected depth whilepreventing excessive damage to the epidermal layer. In a preferredembodiment, the energy-emitting surface is thin microfluidic body 410 asdepicted in FIG. 15 above. In another embodiment in FIG. 19, a jaw arms472A that is of a forceps-type instrument as in FIG. 14, can comprise abipolar metal film electrode 475A overlying a superlattice coolingstructure 450. Each jaw arm can include such an electrode coupled to anRf source 150A to provide for bipolar energy delivery between the jaws.Such a bi-polar jaw structure with active superlattice cooling wouldprevent tissue sticking. It should be appreciated that other thermalenergy-emitting surfaces are possible, such as laser emitters, microwaveemitters and resistive heating elements.

Now turning to FIG. 20, an alternative instrument with thermal energydelivery surface 415 is shown. In this embodiment, the open-endedcapillary microchannels 485 are formed in a body 488 of a selectedmaterial and have a selected cross-sectional dimension to provide acapillary effect to draw liquid media 422 into the capillary channels.This embodiment can be fabricated of a polymer by soft lithographymeans. Alternatively, the tissue-engaging body can be of a ceramic,metal or a combination thereof. As can be seen in FIG. 20, the pluralityof capillary channels have an interior end 492 that communicates with aliquid reservoir 494. In operation, the capillaries will draw liquid 422into the channels by means of normal capillary forces. The capillarychannels 485 further carry a thermal energy emitter about interiorchannel regions for vaporizing the liquid 422 that is drawn into thechannels. The thermal energy emitter is operatively coupled to a sourceselected from the class consisting of a Rf source, microwave source,laser source and resistive heat source. In operation, the capillarieswill draw liquid 422 into the channels 485 wherein vaporization willeject the vapor outwardly from the surface 415 to apply thermal energyto tissue as described in earlier embodiments. The advantage of theinvention is that the capillary channels can continuously draw liquid422 into the microchannels from a substantially static liquid reservoirwithout the need for a substantial pressurization means. At the sametime, the vaporization of the liquid media 422 will cause pressures tocause ejection of the vapor from the surface 415 since that is thedirection of least resistance. The surface 415 can further carry anymonopolar of bipolar electrode arrangement to couple energy to theejected vapor and engaged tissue.

FIG. 21 illustrates an alternative jaw structure 500 for sealing tissuewith first and second jaws 502A and 502B. Each jaw carries a body 410with capillaries channels 420 and vapor delivery ports as in FIG. 15.The jaws structure includes a system that transects tissue by hydrojetmeans that can cooperate with the fluid media source of the invention.Of particular interest, one jaw carries an ultrahigh pressure waterinflow lumen 510 that exits at least one thin linear port 515 whereinthe jetting of water has sufficient velocity to cut the engaged tissue.Depending on the length of the jaws, the jetting port(s) 515 can besingular or plural, an overlapping if required to insure transection ofany engaged tissue volume. In another embodiment (not shown) the jaw canhave a moveable jet member that axially translates in the jaw to cuttissue. Electrical energy can be coupled to a fluid jet to further applyenergy along a cut line. The jetted fluid is received by elongatechannel 525 in the opposing jaw that communicates with extraction lumen540 and an aspiration source. Such a jaw can have an interlock mechanismto insure that the hydrojet cutting means can only be actuated when thejaws are in a closed position. This embodiment provides the advantage ofhaving a non-stick tissue-sealing jaw structure together with atransecting means that operates without moving parts. It should beappreciated that the scope of the invention includes the use of such ahydrojet cutting means to any surgical jaw structure that is adapted toseal tissue or organ margins.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Specific features of theinvention are shown in some drawings and not in others, and this is forconvenience only and any feature may be combined with another inaccordance with the invention. Further variations will be apparent toone skilled in the art in light of this disclosure and are intended tofall within the scope of the appended claims.

1. A system for applying energy to tissue comprising a polymericmonolith with fluidic channels therein, the monolith having atissue-engaging surface for engaging tissue, and a fluid media sourcethat introduces fluid media into the fluidic channels for applyingenergy to engaged tissue.
 2. A system for applying energy to tissue asin claim 1 wherein the fluidic channels have mean cross-section of lessthan 1 mm.
 3. A system for applying energy to tissue as in claim 1wherein the fluidic channels have mean cross-section of less than 0.5mm.
 4. A system for applying energy to tissue as in claim 1 wherein thepolymeric monolith is of an elastomeric composition.
 5. A system forapplying energy to tissue as in claim 1 wherein the fluid media is avapor phase media capable of releasing the heat of vaporization to applyenergy to tissue.
 6. A system for applying energy to tissue as in claim5 wherein the fluidic channels have an increase in cross-sectionproximate the tissue-engaging surface for allowing a vapor to liquidphase transition of the media.
 7. A system for applying energy to tissueas in claim 5 wherein the fluidic channels include ports in thetissue-engaging surface for allowing outflow of vapor from the fluidicchannels to interact with tissue.
 8. A system for applying energy totissue as in claim 1 further comprising thin film nanolattice coolingmeans coupled to the monolith.
 9. A system for applying energy to tissueas in claim 1 wherein the fluid media comprises a conductive liquid incommunication with an electrical energy source.
 10. A system forapplying energy to tissue as in claim 1 wherein the fluidic channelsdefine first and second spaced apart paths each carrying a conductiveliquid in communication with opposing poles of an electrical energysource.
 11. A system for applying energy to tissue as in claim 10wherein said opposing poles of the electrical energy source comprisefirst and second electrode elements carried in said first and secondspaced apart paths proximate the tissue-engaging surface.
 12. A systemfor applying energy to tissue as in claim 2 wherein the elastomericcomposition of the tissue-engaging surface has a substantially thindimension overlying the fluidic channels to allow capacitive couplingtherethrough.
 13. A system for applying energy to tissue as in claim 2wherein the elastomeric composition of the tissue-engaging surfaceoverlying the fluidic channels is fluid permeable.
 14. An instrument forapplying energy to tissue comprising a body having an energy-emittingsurface for contacting tissue and thin film superlattice coolingstructure coupled to the energy-emitting surface.
 15. An instrument forapplying energy to tissue as in claim 14 wherein the energy-emittingsurface comprises at least one electrode.
 16. An instrument for applyingenergy to tissue as in claim 14 wherein the thin film superlatticecooling structure is at least partly interior of the energy-emittingsurface.
 17. An instrument for applying energy to tissue as in claim 14wherein the thin film superlattice cooling structure is at least partlyexposed in a tissue contacting surface.
 18. An instrument for applyingenergy to tissue as in claim 14 wherein the energy-emitting surfacecomprises first and second portions carrying opposing polarityelectrodes.
 19. An instrument for applying energy to tissue as in claim18 wherein the first and second portions of the energy-emitting surfaceare within respective first and second opposing jaw elements.
 20. Aninstrument as in claim 14 wherein the thin film superlattice coolingstructure comprises a stack of alternating thin semiconductor layers.21. An instrument as in claim 14 wherein the thin film superlatticecooling means comprises alternating stacks of alternating thin filmlayers of bismuth telluride and antimony telluride.
 22. An instrument asin claim 14 wherein the thin film superlattice cooling means comprises acircuit including a plurality of thin film layers of at least twodissimilar conductors wherein current propagates heat toward one end ofthe circuit thereby cooling the end of the circuit coupled to theenergy-emitting surface.
 23. An instrument as in claim 14 wherein theenergy-emitting surface comprises a thermal energy source selected fromthe class consisting of a Rf source, microwave source, laser source andresistive heat source.
 24. An instrument for applying energy to tissuecomprising a body having a tissue-contacting surface with a plurality ofcapillaries having open terminations in the surface wherein the interiorend of the capillaries communicate with a liquid source, and a thermalenergy emitter within the capillaries for vaporizing liquid therein. 25.An instrument as in claim 24 wherein the body is at least one of apolymer, ceramic or metal.
 26. An instrument as in claim 24 wherein thethermal energy emitter is operatively coupled to a source selected fromthe class consisting of a Rf source, microwave source, laser source andresistive heat source.
 27. A surgical instrument comprising a jawstructure having first and second axially-extending jaws includingthermal energy delivery means for sealing tissue, and at least onejetting aperture in a jaw in fluid communication with a high pressurefluid jetting source.
 28. A surgical instrument as in claim 27comprising a plurality of jetting apertures having an axial alignment inthe jaw.
 29. A surgical instrument as in claim 27 further comprising atleast one aspiration port in a jaw for receiving fluid jetted from theopposing jaw.